This invention relates to panels and tiles of the type commonly used in ceilings and walls for various industrial, commercial and institutional applications where a contamination controlled environment is desired. Common usages are in the food industry where the minimization and control of microbial foodborne and airborne diseases is critical, and in high technology industries where clean room conditions must be maintained.
These situations require a designated, controlled area in which the processing takes place. For instance, in meat processing plants, there may be separate rooms for slaughtering, de-boning, refrigeration and packaging. Oftentimes, the panels separate the room from various utility resources, such as HVAC systems, which must be maintained. This plenum chamber created by the panels must be readily accessible; hence, the panels must be removable to gain access into the chamber. The need for maintaining a clean, sanitized area is critical to avoid the proliferation of microbial activity. Towards that end, frequent cleaning of the area is necessary. It is therefore necessary to spray down the walls and ceilings. Such harsh treatment requires a panel that is hard and impermeable, and resistant to chemical corrosion and microbial invasion.
There exist foam core composite panels which have a hard, impermeable gel coat facing. These are quite adequate for their intended use of providing resistance to chemical corrosion and microbial invasion, and are able to withstand the harsh spray-down cleaning process. However, the gel coat surface is really only effective where it is in place. There are parts of the foam core panel which do not have the gel coat facing, i.e., the opposite face and the perimeter edges of the panel. Because there are areas on the panel that are not provided with the gel coat facing, the panel is still subject to moisture, chemical and microbial invasion through the unprotected areas. Hence, the panels will still eventually suffer damage to their structural and compositional integrity from these elements.
There have not been any panels or tiles that have adequately addressed the problem of the unprotected foam substrate. Applying the gel coating to all surfaces of the panel can get quite expensive and is not cost effective. Panels that have the gel coating on both face surfaces still, however, have their side edges unprotected. The manufacturing process for these composite panels is such that they are typically cut in tile dimension, leaving the four side edges uncovered by the gel coating and the inner foam substrate exposed. Open edges can still permit water and chemical absorption and microbial contamination. Moisture that is absorbed by the foam substrate will expand and contract during freeze and thaw cycles causing the panel to crack and swell over time. Further, moisture contributes to vapor formation on the surface of the panel which can contribute to contamination. Also, loose particles may become dislodged from the foam core substrate and become airborne, which can contribute to contamination of the processing room area bounded by the panels. Further, open edge panels are structurally weak and are vulnerable to delamination.
While there exists panels that do have completely closed edges, their configuration typically comprises a blunt, truncated edge. While the panel itself may have all the desirable attributes, such as being impermeable and having good structural integrity, the blunt edge can present installation difficulties with suspended ceiling grid systems. Grid systems comprise inverted T-runners having a web structure and hanger wire attachment leaving only minimal clearance over their supportive shelf upon which the panel edge rests. Occasionally, a panel edge must be cut so that it will fit in the available space over the shelf on the T-grid. However, if the edge is cut, the benefit of the closed edge is destroyed, as the interior of the panel would then be exposed. Further, if the tile edge is not cut, its blunt edge may cause the T-grid to bend, leaving a distortion.
Thus, there is a need for a ceiling and wall panel or tile which can provide the structural integrity necessary to withstand the rigorous environmental and maintenance conditions that exist in these aforementioned industries. It is further desirable that these panels be completely resistant to water, chemical and microbial contamination. Further yet, there is a need for a ceiling tile which can be easily removed from a T-grid suspension system to allow access to the plenum area above the tiles.